Fasteners are useful to secure the corners of a disposable absorbent article, such as a diaper. Certain fasteners are refastenable in that they are capable of multiple openings and closures. These fasteners are useful, for example, to attach the absorbent article around the waist of a wearer and maintain the absorbent article on the wearer during use. In addition, these fasteners allow the diaper to be folded or rolled into a tight package for disposal, secured in a disposal configuration, and thereafter more easily disposed in a waste receptacle. When the fasteners are secured in the disposal configuration, the contents of the absorbent article are generally prevented from spilling or leaking out while the absorbent article is being disposed. Examples of these fasteners are generally described in Duncan et al. U.S. Pat. No. RE 26,151, Buell U.S. Pat. No. 3,848,594, Scripps U.S. Pat. No. 4,846,815, Robertson et al. U.S. Pat. No. 4,963,140, Scripps U.S. Pat. No. 5,019,065, Noel et al. U.S. Pat. No. 5,032,122, Zoia et al. U.S. Pat. No. 5,053,028, Seth U.S. Pat. No. 5,611,789, and International Publication No. WO 02/056814 A1. These fasteners can include a mechanical fastener and/or an adhesive fastener.
Mechanical fasteners capable of refastenability include hook (or mushroom-shaped) fasteners engageable with loops, and variants thereof. These fasteners are generally rigid, but can be damaged during high-speed processes used to manufacture commercial quantities of consumer goods such as diapers. These processes are often referred to in the art as “conversion” processes. Damage occurs when the fasteners become inadvertently exposed to the processing equipment, which can destroy the fastener or diminish its usefulness by, for example, crushing elements of the fasteners. Hook fasteners are particularly vulnerable to such damage, but other mechanical type fasteners such as buttons, tab and slots, or the like can also become damaged, torn, or otherwise adversely affected by high speed processing.
Attempts to address these vulnerabilities have included designing fasteners and delicate elements thereon that are less likely to come into contact with the high-speed processing equipment. Generally, the designs include folding the fastener into a “closed” position and maintaining the fastener in that position throughout the manufacturing process and until the article is ready for use. Fasteners are generally maintained in the closed position by a pressure sensitive adhesive and a release surface, fused welds, or mechanical engagement of fastener elements directly into the article fabric adjacent the fastener.
Seth U.S. Pat. No. 5,611,789, for example, discloses a fastener design similar to designs that have been incorporated into commercially-available disposable absorbent articles. The '789 patent describes a fastener arrangement where mechanical fastening elements are disposed on a fastening tab formed of a backing and an adhesive layer. The adhesive layer also permanently attaches the fastening tab to a portion of the disposable absorbent article, which article includes a backsheet and a topsheet. A release tape is affixed to the topsheet by an adhesive and the release tape permits the user to release the fastening tab from the fastener arrangement prior to use, for example, and thereafter attach the fastening elements to a complementary fastening surface on the article when the article is ready for use, or attach the adhesive layer (exposable by the release tape) to other portions of the article after the article has been used and is ready to be disposed. While this fastener arrangement is suitable for maintaining the fastener in a closed position prior to use, it also requires materials such as a release tape and an adhesive layer (exposable by the release tape) to maintain the fastener in the closed position. These materials can complicate the conversion process and, or course, add to the costs of the article.
Heindel et al. U.S. Pat. No. 5,961,761 discloses another fastener design similar to designs that also have been incorporated into commercially-available disposable absorbent articles. This design does not require the adhesive layer and the release tape to maintain the fastener in the closed position prior to use. Specifically, mechanical fastening elements (i.e., hooks) on the fastener are releasably engageable with an inside surface of an ear tab on the article to maintain the fastener in the closed position prior to use. According to the '761 patent's disclosure, the ear tab to which the fastening elements releasably engage is formed of a material such as that used to form an outside cover or inside liner of the article, such as films, nonwoven materials, woven or knit materials, foams, composites, and laminates thereof.
Although the design disclosed in the '761 patent does not, according to the '761 patent's disclosure, require a release tape and or an adhesive layer exposable by the release tape, that design also does not ensure that the fastener will actually remain suitably engaged with the surface of the ear tab prior to its use and, therefore, does not ensure that the fastener (and the fastening elements thereon) will avoid damage from the conversion process. Specifically, the fastener in its closed position may encounter stresses during the conversion process stronger than the (peel) force and shear strength required to open the fastener. The fastener will undesirably open in response to those stresses, and, when opened during the conversion process, the fastening elements on the fastener will be vulnerable to damage by the conversion process equipment. If damaged, of course, the fastener will not work as intended to form a closure with other portions of the article.
One response to the problems associated with the fastener design disclosed in the '761 patent might be to incorporate loop fastening elements that complimentarily engage the hooks on the fastener. With this modification, a stronger (peel) force and shear strength are required to open the fastener. However, use of both of the hook and loop fastening elements to hold the fastener closed may provide a (peel) force and shear strength in excess of that ordinarily desired by the user (e.g., a parent) when attempting to place and fit the article around the waist of the wearer (e.g., an infant). For example, when the peel force is too great, the user will have difficulty in opening the fastener, while also handling and positioning the wearer. Consumer testing has shown that fastening systems exhibiting a peel force of greater than about 12 N/inch, as measured by a T-Peel Test, are viewed as being difficult to separate. Consumers tend to prefer a fastening system exhibiting a peel force of less than 10 N/inch, as measured by the T-Peel Test.
The foregoing discussion of conventional fastener designs identifies deficiencies in those designs such as, for example, the expense necessitated by the use of extra materials (e.g., release tape/surface and the adhesive exposed by the tape/surface), extra capital equipment (required to process a fastener having the extra materials), undesirably weak closure bonds that open during the diaper conversion process (resulting in damage to the fastener elements), and undesirably strong closure bonds that make use of the article by the consumer difficult and possibly impractical. Even if the expense necessitated by the extra materials were of no concern, the presence of such materials presents other potentially undesirable effects. For example, a pressure sensitive adhesive (and release tape) may undesirably adhere to the skin of the article's wearer (e.g., an infant) or to the hands of the article's user (e.g., a parent) when placing the article on the wearer. This problem might compel the article's user to select a different product that is less likely to offer this problem.
Accordingly, it would be desirable to provide a fastening system that eliminates the necessity of certain materials used in conventional fastening systems. Furthermore, it would also be desirable to provide a fastening system that maintains the structural integrity and conveniences that consumers have come to expect. Still further, it would be desirable to provide a fastening system that provides a temporary releasable bond maintaining the fastener in a closed position during processing and until ready for use. It would also be desirable to provide consumer goods, such as disposable absorbent articles, that incorporate such a fastening system.